Basic Documentation
Table Of Contents
- About this Application Guide
- Chapter 1–Introduction
- Chapter 2–Goals of the Laboratory Environment
- Chapter 3–Unique Ventilation Needs of a Laboratory Facility
- Chapter 4–Ventilation Systems Classification
- Chapter 5–Laboratory Facility Exhaust Systems
- Chapter 6–Laboratory Containment Units - Ventilation
- Chapter 7–Room Ventilation, Makeup Air, and Pressurization Control Systems
- Chapter 8–Laboratory Temperature and Humidity Control Systems
- Chapter 9–Laboratory Emergencies - Ventilation System Response
- Chapter 10–Laboratory Ventilation System - Validation
- Chapter 11–Laboratory Ventilation System - Commissioning
- Glossary
- Index
Chapter 3–Unique Ventilation Needs of a Laboratory Facility
Biosafety Level 2
This classification usually applies to the largest number of microbiological/biomedical
laboratories. Although some of the substances present may be infectious, they may be
worked on open benches provided that the potential for aerosol release is very low. Apart
from providing an adequate minimum ventilation rate, the room supply airflow rate must be
sufficient to replace the amount of air being exhausted from the room and any biological
safety cabinets that are present. Note that adequately filtered air that flows through the Class
IIA type of biological safety cabinets (very often used in a Biosafety Level 2 laboratory) may
be returned to the room and thus does not increase the amount of air exhausted from the
room. (See the Laboratory containment units - ventilation section for specific details on
biological safety cabinets.) The Biosafety Level 2 lab room must be designed for thorough
cleaning and provisions must be made in the facility for sterilization of apparatus and
decontaminating biological waste from the room. Therefore, room ventilation components
such as supply air diffusers and exhaust air grills must be suitable for periodic
decontamination and washdown.
Biosafety Level 3
Since this classification applies to laboratory rooms that work with infectious agents that are
transmissible as aerosols, the requirements are quite stringent. Biosafety Level 3 rooms must
have all of the provisions of Biosafety Level 2, plus they must utilize biological safety cabinets
for all work being done in the room. The lab must also be separated from other building areas
and a Biosafety Level 3 room requires a double door entry arrangement. Ventilation system
provisions for Biosafety Level 3 requires single pass conditioned airflow. In addition, the room
static pressure must be negative to ensure against outward airflow. Occasionally, there will
be a need to filter all biological safety cabinet exhaust from the room with a high efficiency
particulate air (HEPA) filter. The need to maintain an effective room barrier without
penetrations makes it advantageous to use a dedicated room HVAC system located within
the laboratory unit itself.
Biosafety Level 4
Biosafety Level 4 are seldom present in most laboratory facilities. It is referenced here mainly
to complete the description of the different biosafety laboratory classifications. Biosafety
Level 4 activities require all of the Biosafety Level 3 provisions, plus utilization of the highest
classification (Class 3) of biological safety cabinet. Laboratory entry and exit precautions are
extensive and it is desirable to physically isolate the room from other parts of the overall
laboratory facility. The room construction is more stringent and the ventilation system must
be dedicated only such laboratory rooms. All intake air and all air exhausted from the lab or
any containment unit must be HEPA filtered. The temperature and humidity of these
laboratories is typically required to be closely controlled as required by the nature of the
substances present.
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